Means for automatically relieving the pressure on pressure members when the same are subjected to undue stress



E. ABBOTT ET AL MEANS FOR AUTO TICALLY RELIEVING THE, PRESSURE ONPRESSURE MEMBERS WHEN THE SAME ARE SUBJEOTED T0 'UNDUE- STRESS FiledJune 11. 1926 May 10, 1927. 1,628,297

Patented 'May 10, 1927.

u es STATES mm wes;

WILLIA E NEST ABBOTT, 0 ROCHDALE, AND JOHN ROBERT ELGEY, or LITTLE.

soaonen, ENGLAND, ASSIGNORS TO GEORGE SPENCER,

LIMI OIE Lonnon, ENGLAND, A COMPANY 01* GREAT BRITAIN.

MoUL'roN & oo EANY,

MEANS Eon AUTOMATICALLY BELAIEVING THE Passes-RE on PRESSURE MEMBERSWHEN THE 'sAME ARE SUBJECTED To" E UE STRESS.

- Application filed June 11, 1926, Serial no. 115,412, and n GreatBritain November 12, 1925.

This invention has reference to machines embodying members sub ected topressure andwlnlst the mvention 1s particularly applicable toj-therollers of rubber mills or other machines comprising. pressure rollersit" is not restricted to 'such applications but is capable of being usedin numerous cases where pressu're'members are liable to be subjected toundue stress." 1

Rubber mills are liable to be severely strained" and considerable damagetothe same is often caused by hard foreign matter, such as'metal bodies,being fed with the rubber between the rollers of the mill.

The rollers of such mills are adjusted towards each other by screwedspindles that work in internally serewed bushes mounted in the mainframesand' inorder to prevent costly partsfsuch as the main frames,being broken under the stresses'tthat arise upon foreign matters asabove stated passing betweenthe rollers it has already been proposed,and 'indeedit is at present customary, to so makeand mount these bushesthat they will fracture and release the pressure on to result in'abreakage of the main frames or other costly partof the mill. It is.however, to be noted that these bushes are necessarily substantialarticles that are certainly not cheap to produce being internallyscrewthreaded and machined to fit the bearings formed therefor in themill frames.

The object of the presentinvention is to provide simple and efficientmeans where by, upon undue stress on the rollers, the pressure thereonis 'automatically' released without fracture of these bushes orany otherpart that will entail appreciable cost to relace. p For this purposemeans according to the invention comprise a frangible body that normallycloses an outlet passage from a chamber filled with grease orothersuitable medium or liquid that is compressed by movement of theroller or pressure member consequent, upon same being subjected to unduestress, the arrangement being such that the frangible body will bebroken and allow the escape of the grease or other medium upon thepressure exceeding the predetermined pressure the frangible body isdesigned to withstand.

In an embodiment of the invention in its application to a rubber mill,there is interposed between" each screwed spindle them'a- I nipulationofwhich effects the adjustment of the rollers relatively to each other,and the corresponding roller or roller bearing, a plunger working withina cylinder charged with grease or other suitable medium or liquidbetween the saidplunger and a piston or block also working in saidcylinder, the

inner end of the screwedoperating spindle abuttlngupon thewsaid pistonor block so that upon rotation of the screwed spindle, the piston orblock is forced within the cyl incler and, through the grease or liquidthere- 9 in which is practically incompressible, forces the plungeroutwardly and thereby efie'cts movement of the roller. Frangible meansof any suitable character'are provided whereby 1 the grease or' liquidis released from said" cylinder upon undue stress Such as would ariseupon the plunger moving inwardly byreason of'the rollers ofthe millsbeing forced away from each otherby the fact of a hard body being fedbetween them. The said releasing means constitute safety devices and maybe of any suitable character. A simple,

rial such as cast metal, glass, or glazed earthand'at present thepreferred form of such" 'means, consists of a disc of frangiblemateenware placed over an axial boring formed through thepiston or'blockand the screwed operating spindle,'the said frangible disc be 1 ingsubjected on one side to the pressure of thegrease or liquid within thecylinder so that upon undue p'res'sure'thedisc will be i fractured andthe grease or liquid will con sequently be free to escape through theboring of the operating Spindle as the plunger moves inwardly, torelieve the pressure on the rollers of the mill. disc is of any desiredpredetermined thickness to withstand a given load.

A specific construction of an arrangement embodying the invention asapplied to a rubber mill is illustrated in the accompanying drawings,Fig. 1 being a longitudinal section and Fig. 2 an end view.

The screwed roller adjusting spindle 1 works as usual in an internallyscrewed bush 2 that is removably mounted in the usual way in the millframe 3, that is to say the bush is formed with laterally extending lugsThe frangible 2 which engage, after the manner of a bayonet joint,behind lugs 3 projecting inwardly from the bore oi the hole in the millframe 3 within which the bush 2 is arranged. The internal screw threadof the bush extends from the outer end of the bush to about midway ofthe length thereof and, beyond the termination of the screw thread totheinner end of the bush, the bush is bored out to form a cylinder withinwhich is fitted a plunger that extends through V the inner end of thebush and bears at its outer end on the bearing. not shown, of the rollerto be adjusted. Fitted on the inner end of the plunger 5 is a leathercup 6. Also arranged to work in the cylindrically bored portiond of thebush 2 is a short piston or block 7 fitted with a leather cup 8, thispiston and the leather cup having a cent 'al hole 9 formed therethroughin alignment with an axial bore 10 formed through the operatingspindle 1. The face of the piston or block 7 bearing the leather cup 8is formed with a recess 11 and inserted in said recess is a frangibledisc 12 of suitable material, such as cast iron, that closes the hole 9formed in the piston and thereby seals the space in the cylindrical borest oi the bush between the piston or block 7 and the plunger 5. The saidspace is filled with grease or other suitable medium or liquidhereinafter referred to as grease.

The arrangement is such that upon screwingup' the spindle 1 the pistonor block 7 is moved in the cylindrical bore a and consequently moves theplunger 5 outwardly through the relatively incompressible body of greasebetween the piston. or block 7 and plunger 5. The mill roller is therebyadjusted. Should undue pressure be exerted on the plunger 5 in an inwarddirection, such as would be the case upon a hard foreign body passingbetween the rollersot the mill, such pressure will be exerted throughthe grease on the frangible disc 12 which will consequently break whenthe predetermined load for which the disc is de signed is exceeded sothat the grease will then. be forced through the axial boring 10 of thespindle 1, whereupon the mill rollers will be immediately released frompressure. It is then a simple matter to release the obstructing bodyfrom between the rollers, inserta new disc 12 within the piston or block7, recharge the cylindrical bore 4c 01' the bush 2 with grease betweenthe piston or block 7 and plunger 5 and again adjust the rollers asdesired. 1t will be appreciated that the cost of the frangible disc 12is practicall negligible. r

The distance between the leather cups 6 and 8 is such that when the disc12 is fractured the plunger 5 can move inwardly sullicient to enable thegear wheels on the ends of the rollers to move out of mesh.

It is to be understood that the invention is not restricted in itsapplication to the rollers of rubber mills butthat it can be applied toother machines comprisinjgprea sure members or rollers in associationwith which it is desired to provide means for ensuring that unduestresses on the :same

shall not result in damage to the machine lVhat we claim is i i 1. Apressure relieving device, comprising a support provided with ascrewthreaded hole and a pressure chamber for fluid, a screw torapplyingpressureengaging with the said hole and having an outlet; forthe fluid, a piston slidable in thepressure chamber and bearing againstthe end o i the screw and having a longitudinal passage, animperforatedisk of frangible material:normally closing the said passage, and aplunger slidable in the pressure chamber and open ated by the pressuretherein. i i

2. A pressure relief device as set forth in claim 1. the said outlet andlongitudinal passage being arranged axially in linewith each other andupon theaxis of the said screw and pressurechamber.

3. A pressure rellevmgdevi WILLIAM banner ABBOTT. JOHN ROBERT ELGEY. iti vce as set forth in claim 1, the said piston and plunger being

